用J2ME在移动设备上实现动画

import java.util.*;

import javax.microedition.lcdui.*;

// 定义了一个动画，该动画其实只是一系列相同大小的图片

// 轮流显示，然后模拟出的动画

public class AnimatedImage extends TimerTask {;

private Canvas canvas;

private Image[] images;

private int[][] clipList;

private int current;

private int x;

private int y;

private int w;

private int h;

// Construct an animation with no canvas.

public AnimatedImage( Image[] images ){;

this( null, images, null );

};

// Construct an animation with a null clip list.

public AnimatedImage( Canvas canvas, Image[]

images ){; this( canvas, images, null );

};

// Construct an animation. The canvas can be null,

// but if not null then a repaint will be triggered

// on it each time the image changes due to a timer

// event. If a clip list is specified, the image is

// drawn multiple times, each time with a different

// clip rectangle, to simulate transparent parts.

public AnimatedImage( Canvas canvas, Image[] images,

int[][] clipList ){;

this.canvas = canvas;

this.images = images;

this.clipList = clipList;

if( images != null && clipList != null ){;

if( clipList.length < images.length ){;

throw new IllegalArgumentException();

};

};

if( images != null && images.length > 0 ){;

w = images[0].getWidth();

h = images[0].getHeight();

};

};

// Move to the next frame, wrapping if necessary.

public void advance( boolean repaint ){;

if( ++current >= images.length ){;

current = 0;

};

if( repaint && canvas != null && canvas.isShown()

){;

canvas.repaint( x, y, w, h );

canvas.serviceRepaints();

};

};

// Draw the current image in the animation. If

// no clip list, just a simple copy, otherwise

// set the clipping rectangle accordingly and

// draw the image multiple times.

public void draw( Graphics g ){;

if( w == 0 || h == 0 ) return;

int which = current;

if( clipList == null || clipList[which] == null

){;

g.drawImage( images[which], x, y,

g.TOP | g.LEFT );

}; else {;

int cx = g.getClipX();

int cy = g.getClipY();

int cw = g.getClipWidth();

int ch = g.getClipHeight();

int[] list = clipList[which];

for( int i = 0; i + 3 <= list.length; i +=

4 ){;

g.setClip( x + list[0], y + list[1],

list[2], list[3] );

g.drawImage( images[which], x, y,

g.TOP | g.LEFT );

};

g.setClip( cx, cy, cw, ch );

};

};

// Moves the animation's top left corner.

public void move( int x, int y ){;

this.x = x;

this.y = y;

};

// Invoked by the timer. Advances to the next frame

// and causes a repaint if a canvas is specified.

public void run(){;

if( w == 0 || h == 0 ) return;

advance( true );

};

};